Magmatic differentiation in the Huaco granite and its associated Be-pegmatites from the Velasco distrit, Argentina

SARDI, F. G., MURARTA, M. & GROSSE, P.

Revista de la Asociación Geológica Argentina

Scielo (Asociación Geológica Argentina)

Lugar: Buenos Aires; Año: 2011 vol. D p. 189 - 191

0004-4822

The Huaco granite of the Velasco district from Pampean Pegmatite Province shows four district phases (BHG, RPG, APG, MA) from de border of the intrusion towards the margins of the included Be-pegmatites. These phases originated from the same magma source, but show textural, mineralogical and geochemical differences that indicate a continuous sequence of fractional crystallization of the granite, followed by the crystallization of the MA as the first pegmatitic phase. Large ion lithophile elements such as Rb, Ba and Sr can be used as monitors of the magmatic differentiation in the Velasco district. The Rb/Sr and Ba/Rb ratios are good examples of them in order to show such evolution. The Ti concentrations clearly separate the Huaco granite phases from the pegmatite phase. The equation Ti = 60 Rb/Sr is a useful empirical expression for separating between granite and pegmatite crystallization.